Maropitant citrate exhibits rapid absorption, short half-life, and fast clearance in orange-winged Amazon parrots (Amazona amazonica) following subcutaneous and intravenous administration.

Abstract

Objective: To determine pharmacokinetic parameters after IV and SC administration of a single dose of maropitant.

Methods: In this experimental study, adult orange-winged Amazon parrots were administered a single dose of maropitant (1 mg/kg) SC and IV with an 8-week washout period between experiments. Blood samples were collected at 0.5, 1.5, 2, 3, 6, 9, 12, and 24 hours after drug administration for the SC study. For the IV study, samples were taken at the same time points with additional collections at 5 minutes and 36 hours. Plasma maropitant was determined with LC-MS-MS, and pharmacokinetic parameters were calculated using a noncompartmental model.

Results: A total of 8 orange-winged Amazon parrots (2 female and 6 male) were used in this study. Mean ± SD maximum concentration after SC administration was 130.9 ± 24.6 ng/mL and was reached at 0.5 ± 0 hours. Combined terminal half-life after SC administration was 6.67 hours. Bioavailability after SC administration was 85%. Plasma concentration at 24 hours was negligible and nearly identical between SC and IV administrations.

Conclusions: A single dose of 1 mg/kg was well tolerated in all birds IV and SC. Maropitant rapidly attained plasma concentrations following SC administration and had a relatively high bioavailability and short half-life.

Clinical relevance: The results of this study suggest that the currently used doses and dosing intervals for maropitant in psittacine birds do not maintain above-target plasma concentrations considered therapeutic in dogs and may be insufficient to achieve systemic effects comparable to those observed in other species.